Torsional couplings are often encountered between two rotating components that need the ability to provide some relative rotation to accommodate torsional vibrations. For instance, an engine may be utilized to drive a hydraulic piston pump in a fracture rig pumping application. A torsional coupling may be necessary to accommodate torsional vibrations resulting from engine harmonic excitations due to sequential engine cylinder firings, and torsional vibrations may also originate from the pump with each pump stroke of each cylinder. In addition, natural torsional frequencies of various components in the drive line may also be excited and in need of being absorbed and damped.
Co-owned U.S. Pat. No. 7,335,107 teaches a torsional coupling in which torques are transmitted from a first coupling element to a second coupling element by way of an interaction between radially oriented pistons of the first coupling element that are biased into contact with circular arc surfaces on the second coupling element. Torsional vibrations are accommodated by the piston contact surface moving back and forth on the circular arc. This relative rotation between the first and second coupling elements results in movement of the piston into and out of its respective barrel. Some damping occurs due to the presence of lubricating fluid and friction at the piston contact with the second coupling element as well as with its respective barrel. While the '107 patent taught an innovative new type of torsional coupling, there remains room for improvement with respect to damping, wear and design variability to address the torsional demands of different applications.
The present disclosure is directed toward improvements to torsional couplings that utilize radially oriented piston and barrel combinations.